This invention relates in general to telephone accessory systems and, in particular, to a system for interception and transmission of signalling tones on telephone lines.
Telephone calls are charged typically in a three-layered market. In California, for example, telephone calls made are classified into three kinds: local calls, toll calls, and long-distance calls. If the call made by a calling party is made to the called party situated in the same neighborhood or town as the calling party or nearby areas within a few miles, the call is typically a local call. If the called party is located beyond the local calling area of the calling party but within a Local Access and Transport Area (LATA), then the call made is a toll call. Local calls are typically free for residential customers whereas toll calls are charged by the duration of the call. For example, California is divided into eleven LATA's. If the called party is located in a different LATA than that of the calling party even though both parties are in the same state, or if the call is between different states or different countries, then the call is a long-distance call.
The telephone system of this country has undergone tremendous changes since the break-up of the Bell system monopoly. With the court ordered break-up of AT&T, the local telephone company typically retained the monopoly over local calls and toll calls of a particular region of the country whereas long-distance carriers such as AT&T, MCI, Sprint and others would compete for long-distance calls. Recently, however, a number of states have further deregulated the market for toll calls by permitting long-distance carriers to compete with the local telephone companies, so that a telephone user has the option of choosing to use a long-distance carrier as opposed to the local telephone company. Regulators are also considering lifting restrictions on local phone companies so that they can compete in the long-distance call market.
Where both the calling and called parties are located in the same LATA, the call is referred to herein as an intra-LATA call. With the above-mentioned deregulation of the toll call market, consumers can obtain significant cost savings by choosing a long-distance carrier to carry an intra-LATA call as compared to using the local telephone company. For example, California is in the process of adopting a plan to allow long-distance carriers to carry intra-LATA calls. Pacific Bell currently charges $0.97 for a four-minute daytime call between Los Angeles and Anaheim located about twenty-five miles from Los Angeles. The price of this call would drop to $0.56 if competing long-distance carriers are allowed to compete for intra-LATA calls. Competition is expected to further reduce the rate by another 10% or so. See the article, "The California Phone Rush is On," The New York Times, Aug. 11, 1993.
Even though in many states, the consumer has the option of choosing a long-distance carrier as opposed to the local telephone company, consumers typically would have to dial a five-digit access code (soon to be seven-digits) as a prefix to the number of the called party in order to charge the call to a competing carrier instead of the local telephone company. If the consumer does not dial the access code, the call would be automatically carried by the local telephone company. Until central office computer software is introduced to facilitate the choosing of different carriers than the default local phone company, most intra-LATA calls are still made through the default carrier, even though choosing a different carrier offers significant cost savings to the consumer. In states like New York where long distance carriers can now compete with Nynex for intra-LATA calls, for example, it is estimated that the local telephone companies have retained about 95% of the residential market.
It is therefore desirable to provide a system that would enable a calling party to automatically choose the lowest cost route for any call that is being made without having to dial an access code as a prefix.